Hydraulic roof supports and conveyor feed jacks



Nov. 4, 1958 c. M -FRYE 2,859,022

` HYDRAULIC ROOF' SUPPORTS AND CONVEYR FEED JACK-S Y Filed April 5, 1956BY W 5., d*

A'rToRNeYS United States Patent HYDRAULIC ROOF SUPPORTS AND CONVEYORFEED JACKS Colin M. Frye, Saint Andrews, Mitton, near Tewkesbury,

England, assignor to Dowty Mining Equipment Limited, Tewkesbury, Englandy Application April 3, 1956, Serial No. 575,828

Claims priority, application Great Britain April 4, 1955 7 Claims. (ci.26a- 1) This invention relates to mining machinery wherein a 15plurality of roof support units, each comprising a framework having twoor more hydraulic props supporting a roof bar, are connected byhydraulic feed jacks to a structure such as a conveyor framework whichextends along the working face of the mine, whereby the jacks may beoperated when the roof support units are extended to advan-ce theconveyor, or when the roof support units are contracted to advance saidunits towards the working face. A roof support system of the kinddescribed constitutes the subject matter of Patent No. 2,803,444 issuedAugust 20, 1957, on the'co-pending application ofM. C. Potts. Inpractise, the -conveyor may be advanced behind the newly cut face in aprogressive snaking movement under the force `of several feed-jackswhich react against their respective support units. Subsequently, eachSupport unit mayin turn be drawn towards the conveyor and the.-workingface by its feed jack. i Y ,n

As the operation of the props and the jackswill, for

Tapld movement reqmre conslderably more power 'than '35 section 13 isco-extensive with the framework 10, and

can be supplied by hand, it is necessarythat a Source of hydraulic powershall be provided 4with a main pressure conduit and a main returnconduitextending along the apparatus with branch conduits to each roof supportunit.

The system according to the present invention com- 4m prises a singlehydraulic power installation'for all .the prop units across the workingface, having a pressure main and .a return main extending along theconveyor structure in .known manner, but whereas in previous sys.- temsof this general nature flexible brauch pipes have led l from theVpressure and return mains for the control of the 45 props at least, orfor both the props and the jacks, of each individual roof support unit,the present system util- `izes no flexible pipes between the conveyorstructure and the several roof support units, and the -only-exible pipesat al1 therebetween are short lengths which are close to 50 `andprotected by parts of the conveyor structure. Insteadthe-branchyconduits to the props, which otherwise* would be unprotected, extendthrough the piston rod of the jack, which is essentiallya part of thesystem iny any case. Valve devices control the application of hydraulic55 pressure to the props or to the jack, `as circumstances 'require. Thelong, unprotected flexible pipes heretofore used are liable to severedamage and may cause complete failure, since they are located in theworking space. The

present arrangement, utilizing the rigid piston rod for con- Gf) ductinghydraulic fluid to and from the props, substantially eliminates thepossibility of damage, especially s incef the exposed portion of thepiston rod can be, and usually would be, protected by la sliding shieldsuch as is shown in the Potts application referred to above.

As will be apparent, a valvingsystem is required to'insure the correctapplication of `hydraulic pressure to thel jack, or to the props beyondthe jackthrough the piston rod of the jack. This valving system,together with the use of the piston rod as part of the branch conduits,con- 70 stitutes broadly `a part of this invention` r f The. objectofthe present `inventionis to provide a con.

2,859,022 Patented Nov. 4, 1958 n y* n ice 'draulic power supply foroperation of the props and jacks comprises pressure and return mainsassociated with the structure, and, for each roof support unit,valve-controlled conduits branching from the pressure and return mains,`said branch conduits including flow paths which extend to and from theprops through the piston rod and cylinder chambers of the feed jack.

,The invention, as applied to an arrangement in which a conveyor and anumber of associated roof support units are as described in the Pottspatent described above, is illustrated in the accompanying drawing, ofwhich:

Figure 1 shows a conveyor framework in cross-section and an associatedroof support unit,rwith the base of the latter broken away to showinterior details, and

Figure 2 is a hydraulic diagram to illustrate the working of thehydraulic components in the unit.

Referring to Figure l, the conveyor which extends along the coal facehas a framework shown generally at 10. Fixed to the rear side of theframework 10 is 0 a plate 11, a channel-shaped member 12 and secured toprovides a protective support for a hydraulic pressure main 16 and ahydraulic return main 17, both of which extend along the conveyor from asource of hydraulic power to provide power for the operation of eachsupport unit. A reversing valve `18 is fixed to the S-shapedmemberadj-acent the channel-shaped anchorage 12, this reversing valvecontrolling the supp-ly and return of hydraulic uid to the associatedroof support unit in a manner which will subsequently be understood fromthe description of Figure 2. The reversing valve has a control shaft 19and handle 21 by operation of which the pressure and return mains 16 and17 may be brought into corresponding or reversed communication with twoservice pipes 22 and 23 leading from the valve 18. The service pipes 22and 23 lead to connections on the head 24 of the piston rod 14, 4andthese service pipes are preferably exible for the reason that lthe head24 is connected by a universal joint 25 to a vertical pivot pin 26 whoseends are fixed in the channel-shaped member 12. They are short, and arewell protected by the S-shaped section 13.

The roof support unit comprises a box-section base member 27 open at thefront for the reception of the feed jack 15 which is secured by a gimbalring 28 having horizontal pivots 29 fixed in the sides of thebox-section base member 27, the gimbal ring in turn being secured to theforward end of the jack cylinder 31 Iby vertical pivot pins 32. Thesupport unit comprises a front prop 33 and a rear prop 34, the formerhaving a cylinder 35 socketed into a mounting 36 at the forward end ofthe base member 27, and the rear prop having a cylinder 37 socketed intothe rear portion of the -base member 27. The props 33 and 34 have rams38 and 39 which carry an inverted channel-shaped roof bar 41 having aforward cantilever extension 42.

A valve assembly 43 disposed on the base member 27 behindthe mounting 36has a pressurizing valve operable by a controlshaft 44 and a releasevalve operable by a control shaft 45. The front and rear ends of thejack cylinder 31 have pipes 46 and 47 respectively connected to thevalve assembly 43, each pipeu46hand 47 being flexible or, as shown,rendered resilient -.b .yrneans of loops 48 which allow for smallangular movements of the jack cylinder 31 at the gimbalpringv28-Thesepipes 46 and 47 are wholly protected, beingpwithinnthje box-section basemember 27, and are not, in anycase, part of the connection between rtheconveyor andthe roof support unit, Abut rather, a p art of the unititself. Pipes 49 'and 51 respectively connect the cylinders 35 and 37 ofthe props with the valve assembly 43. y

The construction and arrangement of the valves Areferred to will lnow bedescribed in greater detail with reference to the hydraulic diagram ofFigure 2. The reversing valve 18, upon the conveyor, has valve plungers52 and 53 shiftable by a rocker 54 on the control shaft 19 `and loadedtowards the rocker by springs 55 and 56 respectively. In the centralposition of the rocker 54, the plungers 52 and 53 close a pressure port57 which is vconnected by a passage 58 and branch conduit 59 with the.pressure main 16. A feed port 61 opensinto an annular space around acentral stern 62 of the valve plunger 52, while a feed port 63 opensinto -a similar annular space around a central stern 64 of the valveplunger 53, the two spaces being interconnected by a return port 65-which is connected by way of a passage 66 and branch conduit 67 withthe return main 17.

The piston rod 14 of the feed jack 15 has a tubular insert 68 dividing acentral passage 69 which is connected by line 22 with'the feedp'ort 61,from an outer passage 72 which is connected by line 23 with the feedport63. The central Zpassage 69 opens through the piston 74 into thepiston chamber 75 of the jack while the outer passage 72 opens throughan aperture 76 inthe piston rod 14 into the ro'd chamber 77. If thecontrol shaft 19 turns the rocker 54 to lift the plunger 52 so that itcloses the return port 65 but opens the ,pressure port 57, and so thatthe plunger 53 continues to connect ports 63 and 65, then liquid fromthe pressure vmain -16 will pass through passage 58, and port 57, feedport 61, pipe 22 and central passage 69 into the pist-on chamber 75,while liquid from the rod chamber 77 will ow through aperture 76, outerpassage 72, pipe 23, feed 'port 63, return port 65 and passage-66 intothe return main 17. Assuming no escape of pressure fluid beyond the jack15, this will extend the feed jack 15 while contrary motion of thecontrol shaft 19 will cause contraction of the feed jack 15. When therocker'54 is in its neutral position, as shown, it is evident that bothchambers 75 and 77 of the jack will communicate freely with -each otherand with the return main 17 through the valve '18.

102 which opens under excessive pressure in the branched Iliti/e 96 fromany of the props 33 or 34, to allow liquid to escape to the outlet port103 of the valve 98. Alternatively, both props can be released at willby turning the vport unit forward towards the conveyor.

control shaft and cam 99 to lift the plunger 101 from its seat at 108,in opposition to the spring 109.

The outlet port 103 is connected by a line 104 with two further checkvalves '105 `and 166 in the block 78, the valve 105 permitting ow intothe pipe 46 which is connected ywith the rod chamber 77 of the jackcylinder 31, and the valve 106 permitting ow into the pipe 47 which isconnected with the piston chamber 75. Thus the check valves 105 and 106permit escape of pressure liquid at all times from the relief valve intoeither jack chamber 77 or 75, whichever is at low pressure, and thencethrough pipe 72 and 23 or 69 Iand 22, and the reversing valve 18 to thereturn main 17.

The check valve 79 in the block 78, on the other hand, admitsliquid fromthe rod chamber 77, when this is under pressure-to the pressurizingvalve 83, and when the latter is lu'nseated, liquid may pass in themanner described to both props 33 and 34, and enable the roof barcarried thereby tol `b'eset'against the roof of the mine.

Theroof support unit may include more than two props extending betweenthe base member 27 and roof bar 41.

v1f, for example, a third prop is included, the block 93 will includetwoadditional check valves such as the pair 94 or 89, 95 in similarlyarranged connections be- 'tween the prop, and the pressurizing andrelief valves.

A three-prop unit and its valves are shown in the Potts applicationreferred to above.

The Vfeed jack 15 may 'be used both to advance the 'conveyor framework10'towards the coal face or, when it'hefprop's 33 and 34 vare retracted,to pull the roof sup- In order to advance the conveyor, the handle 21and control shaft 19 'of the're'ver'rsing valve 18 is turned tooscillate the rocker L'S4-so as to lift the valve plunger 52. When thisis done A block 78 is included in the valve assembly 43, bei yond thejack 15. This block 78 has a check Valve 79 therein permitting llow fromthe rod chamber 77 through the pipe 46 to a line'81which is connectedtothe inlet 82 of the pressurizing valve 83. The pressurizing valve 83 hasa spring-loaded plunger 84 which may be lifted by a cam 85 on thecontrol shaft 44 to open the inlet port 82 to an outlet port 86. Theoutlet port 86 is connected by way of a branched line 87 with two checkvali/e588 and 89 which permit flow through lines 49 and 51 into thehydraulic prop cylinders 35 'and 37 respectively, to urge the propplungers upwardly. The check valves `88 and 89 are contained in a block93, included inthe valve assembly 43, which houses two further checkvalves "9'4 and 95 which permit flow through the lines 49 and/51 fromthe prop cylinders 35 and 37 respectively into 'a branched line 96, toallow `lowering of the prop plungers.

The branched line 96 is connected to an inlet. port `97 of a reliefvalve 98,which is operable also as' a release valve Iby means of a cam99 on the controll shaft 45 vand a spring-loaded valve plunger 101. The`in'ner-'endvofthe valve plunger 101 contains `a spring-loaded relief`valve `port 61. and central passage 69 to the piston chamber 75, whileliquid vexpelled from the rod chamber 77 passes through the outerpassage 72, line 23 and port 63 and around the stem 64 of the valveplunger 53 to the return port l66. The pressure liquid in piston chamberpressurizes line 47, but -since check valve 106 remains closed, there isno escape of liquid beyond the latter.

In order to advance the roof support unit, the roof 'bar 41 and props 33and 34 are rst lowered Iby turning "valve 105 or into the piston chamber75 through the check valve 106, whichever is at lowpressure. In theneutral .position of the reversing valve 18 as shown in 'Figure 2, bothchambers 75 and 77 are in communication with the return main 17 throughthe reversing valve 18. If the latter is actuated to start advancing theroof support unit before the props are fully collapsed, the controlshaft"19 is turned to depress the plunger 53 so that pressure liquid isadmitted to the rod chamber 77. The piston chamber 75 is still incommunication with the return main 17, so that liquid expelled by theprops 33, 34 can continue to pass through the release valve 98 and checkvalve 106 into the piston chamber 75 and thence to the return main 17.

At the end of the advance of the roof support unit it is necessary toextend the props 33, 34, and this is done while pressure still acts inthe rod chamber 77 by operating the control shaft 44 of the pressurizingvalve 83 assaos" pressurizing valve 83, and check valves 88 Vand 89-intothe prop cylinders 35 and 37 respectively. When the roof bar 41 has beenset by extension of the props 33, 34, the reversing valve 18 can bereturned to neutral by centralizing the rocker 54 on the control shaft19. Any subsequent slow yielding of the props under pressure on the roofbar 41 will `cause liquid to be expelled` from one or both prop s v33and 34 Vthrough the check valves 94 'and 95 respectively to the inletport 97 of the release valve 98. The springcontrolled relief valve 102mounted 1in the valve plunger 101 is set to yield under the maxitmumpermissible pressure in the props 33 and 34, and alpen this pressurebeing reached, liquid at the inlet port l 97 can escape past the reliefvalve 102 to the outlet port 103, and thence as described through eitherof the check valves 105 or 106 to the return main 17.

Thus, although there is relative movement between the conveyor framework10, with which the pressure and return mains are associated, and theroof support unit on which the props 33 and 34 are mounted, pressure ismade available at the pressurizing valve and low pressure return at therelease and relief valve, through the feed jack 15 without recourse toadditional conduits between the conveyor framework and the roof supportunit.

Although, in the example described, it is only necessary to extend theprops 35, 37 when the rod chamber 77 of the jack 15 is under pressure,it is possible to make pressure also available at the pressurizing valve83 when the piston chamber 75 is under pressure by providing an'additional check valve 110 opening from the pipe 47 into the line 81.

I claim as my invention:

1. Mine roof supporting apparatus for use in connective association witha conveyor structure which extends along the working face of the mine,said apparatus comprising a plurality of roof support units each unit ofwhichv includes at least two hydraulic props operative to extend 'andcontract said unit, a telescopic hydraulic jack having a cylinder partand a rod part, including a piston, of which one part is joined to saidunit and the other part 1s adapted for connection to said conveyorstructure, hydraulic connections at both ends of the cylinder partopening into the cylinder on opposite side-s of the piston, twohydraulic connections adjacent the outer end of the rod part, twolongitudinal passages formed in the rod part to extend between therespective hydraulic connections therein and the oppo-site sides of thepiston thus providing direct communication between the hydraulicconnections on the rod part and the respective hydraulic connections onthe cylinder part, main pressure and return conduits arranged formounting along the conveyor structure to provide a 4common service foral'l the roof' .support units, and for each said unit a jack controlvalve interposed between the main pressure and return conduits and thehydraulic connections on the jack part which is adapted for connectionto the conveyor structure, and prop control valve means interposedbetween the hydraulic props and the hydraulic connections on the jackpart which is joined to the roof support unit, said propy control valvemeans including a plurality of valves closing under pressure of whichone at least opening from a hydraulic connection on the jack provides apressure `Source for extension of the props, and one other at leastopening to a hydraulic connection on the jack provides a low pressurereturn for relief of the props.

2. Mine roof supporting apparatus according to claim l, wherein saidvalve means comprises a pressure control valve connected to saidpressure source and, for each prop, a check Valve opening from saidpressure control valve to the prop, and a pressure release valveconnected to said low pressure return and, for each prop, a check valveopening from the prop to said low pressure `return.

3, Mine roof supporting apparatus for use in associa- .Y G tion with aconveyor structure which extends along the working face of the mine,said apparatus comprising a plurality of roof support units each ofwhich includes a base member, at least two hydraulic props mounted onthe base member, a roof bar supported on said props, and a hydraulicfeed jack including a piston rod part and a cylinder part of which onepart is connected to said base member and the other part is adapted forconnection to said' conveyor structure, said piston rod having twopassages extending longitudinally therein and opening into said cylinderon opposite sides respectively of the jack piston; and hydraulic powersupply means for operation of said props and jacks comprising mainpressure and return conduits arranged for mounting along said structureto provide a common service for all the roof support units, and, foreach roof support unit a feed jack control valve connected to said mainpressure and return conduits, a pair of service conduits connected tosaid feed jack control valve and extending in part through said passagesin the piston rod and through the cylinder on opposite sides of thepiston to terminations beyond the feed jack, and prop control valvemeans interposed between the terminations of the service conduits andthe props, said prop control valve means including a plurality of valvesclosing under pressure of which one at least opening from thetermination of a service conduit` provides a pressure source forextension of the props, and one other at least opening to thetermination of a service conduit provides a low pressure return forrelief of the props.

4. Mine roof supporting apparatus according to claim 3, wherein thecylinder of the feed jack is connected to the base member of the roofsupport unit, and the piston rod is adapted at its outer end forconnection to the structure.

5. Mine roof supporting apparatus for use in connective association witha conveyor structure or the like which extends along the working face ofthe mine, said apparatus comprising a plurality of roof Support unitseach unit of which includes at least two hydraulic props oper- :ative toextend and contract said unit, a telescopic hydraulic jack having acylinder part connected to said unit `and a rod part, including a pistonslidable within the ycylinder part, connected at its external end to theconveyor structure, the rod part being formed with two separate fluidpassages leading from separate connections .at its external end to theinterior of the cylinder part at respectively opposite sides of thepiston, main pressure and'return conduits extending along the conveyorstructure to provide a common service for all the roof support units, ajack control valve for each unit interposed between the main pressureand return conduits and said separate connections at the external end ofthe rod part, and operable to control the sense of relativereciprocation of the cylinder part and the rod part, separate hydraulicconduits connected to the respective ends of the cylinder part, andextending thence to both props, and prop control valve means interposedin said conduits between the cylinder part and the props, including aplurality of valves closing under pressure of which one at least is aforward flow check valve providing a pressure source for extension ofthe props, and including a pressurizing valve intermediate such sourceand the props, and operable under control to admit pressure fluid to theprops to extend them, and a normally closed release valve locatedintermediate the props and the hydraulic conduits connected to therespective ends of the cylinder part, and operable under control tocontract the props.

6. Mine roof supporting apparatus as in claim 5, including a reliefvalve incorporated in the release valve, and biased to remain closeduntil a predetermined maximum prop pressure is attained, and then toopen automatically for relief of any excess above such maximum pressure.

7. Mine roof supporting apparatus as in claim 5,

opposite `side of said release valve to the opposite ends of thecylinder part, and means to open said release valveto contract'theprops.

'References Cited in the le of this patent UNLTED STATES PATENTS Joyoct. 27, 1953 fPerrinct al. Nov. 1-6, '1954v

